1. Technical Field
The invention relates to an active device and an active device array substrate, and more particularly, relates to a dual-channel active device and a dual-channel active device array substrate.
2. Description of Related Art
As electronic technology develops, the thin film transistor liquid crystal display (TFT LCD) having superior properties such as high definition, great space utilization, low power consumption and no radiation gradually becomes a mainstream in the display market.
To satisfy the demand for large-sized and high-resolution TFT LCDs, the thin film transistor is required to have high-mobility carriers, so as to shorten the charge and discharge time. Generally, for the consideration of high mobility, high stability, and low production cost, semiconductor layers of the TFTs in the driving circuit are manufactured with amorphous silicon (a-Si). However, the application of amorphous silicon thin film transistor (a-Si TFT) in high-efficiency circuits is limited by its driving capacity. As a result, amorphous silicon thin film transistor cannot integrate the peripheral high-speed driving circuit and control circuit.
In order to improve the ON-current of the amorphous silicon thin film transistor, and further to integrate circuit layout, reduce device area, and improve pixel aperture ratio, the conventional technique modifies the structure and configuration of the semiconductor channel layer, such as altering channel width and length of the semiconductor layer. However, the conventional technique cannot effectively improve the ON-current due to the limitations of the manufacturing process. Otherwise, the device size of a-Si TFT is increased to improve the ON-current. However, this technique causes reduction of the pixel aperture ratio and decreases the overall brightness of the TFT LCDs, and threshold voltage shift may easily occur. In addition, a dual gate may also be utilized to improve the ON-current. However, the dual gate structure requires a thin film transistor that includes a front channel and a back channel. The back channel may easily cause damage to the channel layer during the manufacturing process. Therefore, the dual gate structure faces the problem that the current may be attenuated easily and the improvement of the ON-current is limited. Moreover, this technique cannot integrate the circuit layout to reduce the device area of TFT, improve pixel aperture ratio, and maintain high brightness.